Aerodynamics discussion

[OrbitalEllipses]

I KNOW I'm getting rear lift at speed; I can feel it. While I agree that would interesting to see, I'll leave it parties with more money, time, and science than I have to mess with. Certain parties that may already be working on a well made diffuser.

[robispec]

OK some real world experiances
Mods FULL Borla ELH exhaust(engine back) no diffuser
Robispec cold air.
Grill master front Grill.
Enkei RPF! 17x9+45 with front on 15mm spacers
Hankook RS3's 245/40/17
Robispec front lower control arms which allow the roll center bump ateer track and anti dive/ camber to be adjusted/corrected
KW coilovers
4 wheel BBK
Car lowered 77mm(3")
Car weight without fuel 2380 Front 57.5% (yes thats right).
Track day at WSIR big track turns 1,2, are 4th 6500 and accellerating 8&9 are flat in 5th @ 7k and 5th @ 5800 @ apex (best lap) at the begining of the day these #'s were not possible because the car was "AERO LOOSE"
taping off 80% of the front grill opening(no change in coolent temps) MY LOUVERS WORK GREAT!
Filling up the gas tank at the start of each run
and adding 50 lbs of Ballast in the spare tire well cured the looseness and made the car easier to drive at all speeds
these weight additions changed the Nose weight % back to 55%
top speeds were 119. Best time was 1:35.083
It's funny because a FI car was there 2800 lbs total weight (58% front)
Full 275/35/18 c-91 hankook slicks
4 wheel BBK
Coilovers
BRZ wing (it's so cute!)
Basicly the same mods but add Turbo sauce.
He ran a 1:34.430 Less than a second faster with DOUBLE the WHP
and talking with him He has the same complaint of the back of the car being very touchy! Even with the extra grip.
So rear down force will be VERY important as we figure out how to get this chassis optomized for the tRACK

[ayau]

Originally Posted by robispec

OK some real world experiances
Mods FULL Borla ELH exhaust(engine back) no diffuser
Robispec cold air.
Grill master front Grill.
Enkei RPF! 17x9+45 with front on 15mm spacers
Hankook RS3's 245/40/17
Robispec front lower control arms which allow the roll center bump ateer track and anti dive/ camber to be adjusted/corrected
KW coilovers
4 wheel BBK
Car lowered 77mm(3")
Car weight without fuel 2380 Front 57.5% (yes thats right).
Track day at WSIR big track turns 1,2, are 4th 6500 and accellerating 8&9 are flat in 5th @ 7k and 5th @ 5800 @ apex (best lap) at the begining of the day these #'s were not possible because the car was "AERO LOOSE"
taping off 80% of the front grill opening(no change in coolent temps) MY LOUVERS WORK GREAT!
Filling up the gas tank at the start of each run
and adding 50 lbs of Ballast in the spare tire well cured the looseness and made the car easier to drive at all speeds
these weight additions changed the Nose weight % back to 55%
top speeds were 119. Best time was 1:35.083
It's funny because a FI car was there 2800 lbs total weight (58% front)
Full 275/35/18 c-91 hankook slicks
4 wheel BBK
Coilovers
BRZ wing (it's so cute!)
Basicly the same mods but add Turbo sauce.
He ran a 1:34.430 Less than a second faster with DOUBLE the WHP
and talking with him He has the same complaint of the back of the car being very touchy! Even with the extra grip.
So rear down force will be VERY important as we figure out how to get this chassis optomized for the tRACK

can you talk about your weight reduction?

[robispec]

what would you like to know

[ayau]

Originally Posted by robispec

what would you like to know

What did you remove/replace to lose ~350lbs?

[robispec]

LOTS O STUFF lol
Please go here and subscribe as I will be discusing this as we flesh out the products we developed.
http://www.ft86club.com/forums/showt...light=robispec
seats, airbags, bumper beams ebrake all 4 corners BBK wheelsfull exhaust replacement mirrors Carbon fiber driveshaft anything not absolutly nessisary like the Rear swaybar
going for 2300 lbs by the REDLINE time ATTACK at BRP in 2 weks

[LeeMaster]

Originally Posted by robispec

...anything not absolutly nessisary like the Rear swaybar
going for 2300 lbs by the REDLINE time ATTACK at BRP in 2 weks

Wait a minute, you plan on doing a time attack without a rear sway bar? Youre talking strict 1/4 mile right or real time attack..? Sorry not trying to derail this topic.

[ayau]

Originally Posted by LeeMaster

Wait a minute, you plan on doing a time attack without a rear sway bar? Youre talking strict 1/4 mile right or real time attack..? Sorry not trying to derail this topic.

Pretty sure it's strictly track.

[markitect]

For you experts, is there a purpose to the vertical fins, on side skirts, and lips. They can't stabilize the car, as they are too close to the side. Do these help with drag around the wheels, or do they just look good?

[Shankenstein]

I've seen these on the McLarenn P1. The vertical fin is just downstream of the front tire. It's combined with a larger vertical fin that runs along the body.

My guess is that the swirling air coming out of the wheel needs to be re-stabilized and directed rearward.

[CSG Mike]

Originally Posted by robispec

OK some real world experiances
Mods FULL Borla ELH exhaust(engine back) no diffuser
Robispec cold air.
Grill master front Grill.
Enkei RPF! 17x9+45 with front on 15mm spacers
Hankook RS3's 245/40/17
Robispec front lower control arms which allow the roll center bump ateer track and anti dive/ camber to be adjusted/corrected
KW coilovers
4 wheel BBK
Car lowered 77mm(3")
Car weight without fuel 2380 Front 57.5% (yes thats right).
Track day at WSIR big track turns 1,2, are 4th 6500 and accellerating 8&9 are flat in 5th @ 7k and 5th @ 5800 @ apex (best lap) at the begining of the day these #'s were not possible because the car was "AERO LOOSE"
taping off 80% of the front grill opening(no change in coolent temps) MY LOUVERS WORK GREAT!
Filling up the gas tank at the start of each run
and adding 50 lbs of Ballast in the spare tire well cured the looseness and made the car easier to drive at all speeds
these weight additions changed the Nose weight % back to 55%
top speeds were 119. Best time was 1:35.083
It's funny because a FI car was there 2800 lbs total weight (58% front)
Full 275/35/18 c-91 hankook slicks
4 wheel BBK
Coilovers
BRZ wing (it's so cute!)
Basicly the same mods but add Turbo sauce.
He ran a 1:34.430 Less than a second faster with DOUBLE the WHP
and talking with him He has the same complaint of the back of the car being very touchy! Even with the extra grip.
So rear down force will be VERY important as we figure out how to get this chassis optomized for the tRACK

I'm a bit disappointed that I didn't go now. Spent the day mulling over the events of the weekend and possible courses of action.

I didn't think the car was loose at WSIR, but I was also driving a heavily understeer biased setup at the time. Hopefully we'll have another opportunity to visit WSIR soon to do some experimenting with aero.

Now you know why half that front opening is faux from the factory! :p

IIRC, my Vmax was higher when I ran. I'd speculate lower rolling resistance and aero drag from smaller/higher offset wheels with smaller tires...

I believe I was running a muffler delete rather than an axleback at the time too, but the car was so pushy that I never noticed the rear getting loose...

[OrbitalEllipses]

Most if the fins are located just before the rear tire on the kits for these cars, so it's not serving the same purpose as the super engineered McLaren.

The thing that side skirts really do is limit the air coming underneath the car from the sides such that stability is gained...at least from my very basic understanding.

[Ben_G]

Originally Posted by robispec

OK some real world experiances
Mods FULL Borla ELH exhaust(engine back) no diffuser
Robispec cold air.
Grill master front Grill.
Enkei RPF! 17x9+45 with front on 15mm spacers
Hankook RS3's 245/40/17
Robispec front lower control arms which allow the roll center bump ateer track and anti dive/ camber to be adjusted/corrected
KW coilovers
4 wheel BBK
Car lowered 77mm(3")
Car weight without fuel 2380 Front 57.5% (yes thats right).
Track day at WSIR big track turns 1,2, are 4th 6500 and accellerating 8&9 are flat in 5th @ 7k and 5th @ 5800 @ apex (best lap) at the begining of the day these #'s were not possible because the car was "AERO LOOSE"
taping off 80% of the front grill opening(no change in coolent temps) MY LOUVERS WORK GREAT!
Filling up the gas tank at the start of each run
and adding 50 lbs of Ballast in the spare tire well cured the looseness and made the car easier to drive at all speeds
these weight additions changed the Nose weight % back to 55%
top speeds were 119. Best time was 1:35.083
It's funny because a FI car was there 2800 lbs total weight (58% front)
Full 275/35/18 c-91 hankook slicks
4 wheel BBK
Coilovers
BRZ wing (it's so cute!)
Basicly the same mods but add Turbo sauce.
He ran a 1:34.430 Less than a second faster with DOUBLE the WHP
and talking with him He has the same complaint of the back of the car being very touchy! Even with the extra grip.
So rear down force will be VERY important as we figure out how to get this chassis optomized for the tRACK

Do you have pics of the taped up front end?

[Shankenstein]

On a similar note, the McLaren P1 and the Lamborghini Aventador have 2 layer diffusers. How effective are these at generating downforce, while still diffusing the wake cross-section?